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Forum Replies

  1. Hi Rene,
    What happens when Portfast is enabled on a port but BPDU filter is not globally enabled and the port receives a BPDU.

    Thanks,

  2. Chandru,
    The port will lose its portfast status, and will continue to function like a normal port (without Portfast). It will not be disabled unless BPDU Guard was also enabled.

    FYI: Rene has a Lesson related to this topic here

  3. Hi Rene,

    It means Portfast enabled interface still sends and recevies BPDU.
    what happens when We configure BPDU filter ?

  4. Hello Tejpal

    What actually happens when a portfast configured port receives a BPDU actually depends on the configuration.

    1. In simple STP (IEEE802.1D), a portfast port will be reset back to a normal port participating in STP if BDPUs arrive on the port. If a physical L2 loop is created on such a port, it will result in a temporary L2 loop until STP reconverges. This is why you will see this warning when configuring portfast (notice the word “temporary”:

       %Warning: portfast should only be enabled on ports connected to a single
        host. Connecting hubs, concentr
    ... Continue reading in our forum

  5. Hello Swapnil

    If a situation like this happens, the port that is configured with portfast will receive a BPDU. What happens next depends on how the port is configured. Take a look at the previous post above to see more details.

    In general it is best practice to enable portfast only on ports that have end devices connected to them and not other switches.

    I hope this has been helpful!

    Laz

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